JPS6256899A - Melting tank for reprocessing nuclear fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial field of application] Nuclear fuel reprocessing equipment for nuclear couplant [Prior art] (1) Batch-type nuclear fuel reprocessing melting: Packing of soda first
1, and its operation will be fully explained below.

First, open the melting cylinder lid 5α and put the basket 2af into the melting cylinder 1α, then open the guide pipe lid 7a and pass the fuel sheared piece 3G through the guide pipe 6alr to the basket 2cL.
After the melting tube lid 5α and the guide tube lid 7α are fully closed. Next, passing steam into the heating jacket 158,
Heat the melting cylinder 1ai. As a result, the temperature of the solution increases, a dissolution reaction starts, and the solution begins to flow in the negative direction.

When the concentration of the solution (NHO3) decreases due to the dissolution reaction, a new solution is added into the storage tank 8a from the solution inlet pipe 9α. The reaction gas generated by the dissolution reaction and the water vapor generated when the solution is heated are -
-> direction and is discharged out of the υ system through the reaction gas outlet pipe 10cL.

When the dissolution is completed, the pulp 4af is opened and one dissolved solution is sent to the next step. Next, the pulp 4a is closed, and the new dissolved solution is put into the liquid storage tank 8G and the melting cylinder 1cL through the whole dissolved liquid inlet pipe 95, and the liquid storage tank 8a, the melting cylinder 1α, the basket 2a, and the fuel shearing piece 3a are washed. After cleaning is completed, open the melting cylinder lid 5ISt, take out the basket 2a and the fuel shearing piece 3a from the melting cylinder 1α, and insert a new basket 25.
into the melting cylinder 1α. Thereafter, the steps described above are repeated, and the entire melting operation of the fuel shear pieces 3a is performed again.

(2) The structure of a rotary continuous nuclear fuel reprocessing melting tank is shown in FIG. 12, and its operation will be explained below.

Baskets 26 are installed radially in the rotating part 16, and the fuel sheared pieces are transferred from the shearing machine 106 to the introduction pipe 3b1.
is introduced into the basket 2b and dissolved in the dissolving liquid 9b.

The rotating part 1h rotates in the direction of the arrow, and when it reaches the upper half position, the fuel sheared pieces are transferred by gravity to the cleaning tank 5b through the discharge pipe 46t.

This rotating part 16 is supported by a row''-) 6b,
The rotational driving force is provided by a nine-gear drive device 86 installed on the top cover 7b.

[Problem that the invention seeks to solve]

(1) In the hatch-type dissolution tank, each process, such as the loading process of the basket and fuel sheared pieces, the dissolution reaction process, the dissolving liquid removal process, the cleaning process, and the discharging process of the basket and fuel sheared pieces, is performed in an independent batch system. It has been adopted.

For this reason, all of the above-mentioned processes proceed in series, resulting in extremely low work efficiency.In order to expand processing capacity, it is necessary to shorten the time required for each process, such as by shortening the melting time. Alternatively, it was necessary to provide multiple dissolution tanks.

Also, because the basket in a conventional dissolution vessel is fixed in an open position during the dissolution reaction process, the fuel shear pieces are moved only a little during the dissolution reaction, and new dissolution liquid is not introduced into the nine fuel shear pieces. Insufficient supply lengthened the dissolution reaction time, which also contributed to the decrease in efficiency.

(2) In the rotary continuous melting tank, the rotating part 1b that holds the fuel shearing pin is rotated by the roller 6 that holds the entire weight of the rotating part 1b.
The nitric acid solution 9b inside the outer case 7b is removed by the sliding rotation of 6.
Rotate in or in nitric acid vapor.

That is, the entire weight of the rotating part 16 is applied to the roller 6b, and the rotating part 1b is not slid in a high-temperature nitric acid atmosphere by the heater 116.

Corrosion and wear of the roller 6b and the support part of the outer case 7b,
Problems such as damage cannot be avoided. Further, if the roller is damaged, it becomes difficult to drive the rotating portion 1b due to its jamming. It is easily understood that remote maintenance for replacing damaged or worn parts would be extremely difficult due to the large number of parts involved. Particularly in the nuclear power field, a structure that is particularly easy to maintain remotely is required due to the presence of radiation sources.

[Means for solving problems]

(1) Do not place sliding parts that support heavy rotating parts in a nitric acid atmosphere.

(2) Instead of bevel and pinion gear drive, the rotating shaft is directly driven, and instead of roller support for the rotating part, the rotating shaft is supported by bearings.

(3) The rotating shaft bearing should be placed outside the cell so that it can be directly maintained.

[For production]

The rotary body including the radial baskets continuously processes the fuel sheared pieces supplied from the supply chute in the melting tank and discharges them from the discharge chute. A bearing provided outside the melting tank supports and drives the rotating body without being exposed to corrosion caused by the melting solution.

[Embodiment 1] An embodiment in which the rotating shaft is supported at both ends is shown in FIGS. 1 to 3. The fuel assembly is sheared into sheared sections 2 of 30-591 m by a shearing machine and introduced via a distributor into the lower basket 3 of the melting tank by a gravity chute. The rotating body 1 includes radial baskets 3 partitioned by perforated partition walls as shown in FIG. 1, and a rotating shaft 4 is supported by a bearing. The supply chute 5 and the discharge chute 6 of the sheared pieces 2 are attached to and fixed to a fixed slab 7. Inside the fixed slab 7, a nitric acid solution is maintained at a liquid level 8 such that the lower basket is submerged. Fixed slab 7
A heater 16 for heating nitric acid is attached to the tank. The rotary body 1 is externally rotated by a rotary drive body 11 in accordance with the times for supplying, melting, discharging, etc. the fuel sheared pieces 2. The fuel sheared fragments 2 introduced from the supply chute 5 enter the dissolution tank lower basket 3, and the fission products and uranium (IJI plutonium (P%)) are dissolved in nitric acid. The shearing piece 2 is caused by the rotation of the rotating body 1,
When it reaches the upper half of the circle, it falls due to gravity, is discharged from the discharge chute 6, and is sent to a cleaning tank (not shown). In this way, the fuel shear pieces 2 can be dissolved continuously. A seal 15 is provided at the rotating shaft penetrating portion to prevent nitric acid droplets or gas from leaking to the outside during rotation. Further, water vapor generated by heating the reaction gas and the solution is sent to a post-treatment step through a gas vent 9.

[Example 2] In the above-mentioned Example 1 (Figs. 1 to 3), the supply chute 5 and the discharge chute 6 are both arranged on one side of the rotating body 1, but since both ends are supported, it is difficult to arrange them on one side. In some cases, as shown in FIGS. 4 to 6, the supply chute 5' and the discharge chute 6 can be arranged separately on both sides of the rotating body 1 to maintain balance. The sheared pieces 2 are introduced from the feed chute 5' into the basket 3 via the holes 1 (l) in the side wall of the rotor.The introduction of the fuel sheared pieces 2 from the feed chute 5' into the basket 3 is also due to gravity; The introduction position is
In order to lengthen the residence time in nitric acid as much as possible, it is preferable to configure it so that it is not introduced into the basket immediately below, but is shifted to the opposite side of the rotation direction.

When introducing the liquid into the basket directly below, it is best to rotate the liquid surface in the opposite direction to the normal rotation, and then complete the normal rotation to lengthen the retention time.

[Embodiment 3] FIGS. 7 to 9 show an embodiment in which the rotating body 21 is supported on one side by a cantilever. In the figure, 21 is a rotating body, 22 is a fuel shearing piece, 23 is a basket provided radially inside the rotating body 1, 24 is a rotating shaft of the rotating body l,
25 is a supply chute for sheared pieces; 26 is a discharge chute; 2
7 is the fixed slab, 28 is the liquid level in the fixed slab 27, 29
is a gas vent provided above the fixed slab 27.

The rotating shaft 24 is supported by the bearing 12 and reversely rotated by the rotary drive body 11. The seal 35 seals the portion where the rotating shaft 24 passes through the fixed slug 27.

[Example 4] In Example 3 (Figs. 7 to 9), the introduction chute 25 and the discharge chute 26 were provided on the same side of the fixed slab 27, but as shown in Fig. 10, the supply chute 25 ' may be provided on the opposite side of the discharge chute 26. In FIG. 10, the reference numerals corresponding to FIGS. 7 to 9 indicate corresponding members, and 30 is a hole provided in the side wall of the rotating body 21, from the supply chute 25' to the hole 3 (through l to the basket). At 23 the sheared piece 22 is introduced.

Note that the functions of the apparatus shown in Examples 2 and 3.4 are those of Example 1.
This is substantially the same as that described in .

〔Effect of the invention〕

By continuously supplying and discharging the fuel shear pieces into the rotating body, all the fuel shear pieces can be efficiently processed continuously.

Further, since the sheared pieces in the nitric acid solution move while rotating in the nitric acid solution, the solution undergoing the dissolution reaction and the sheared pieces are sufficiently stirred and mixed to promote the reaction.

Furthermore, since the structure has no metal on the sliding parts that support the weight of the rotating parts in the nitric acid atmosphere of the melting tank, reliability against corrosion, abrasion, and biting by foreign objects is dramatically improved, and safety against breakage is greatly improved. It can be increased.

In addition, since the driving device for rotation can be disposed outside the entire melting tank cell, replacement and maintenance of dynamic tools such as motors and sliding parts becomes easy.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of the first embodiment of the nuclear fuel reprocessing melting tank of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 4 is a side view showing a partial cross section of the gold of the second embodiment, FIG. 5 is a cross-sectional view of V=V in FIG. 4, and FIG. 7 is a side view of the third embodiment, partially shown in cross section, FIG. 8 is a sectional view taken along the line ■-■ in FIG. 7, FIG. 9 is a view taken along the arrow ■ in FIG. 7, and FIG. FIG. 11 is an explanatory diagram of a conventional batch-type device, and FIG. 12 is an explanatory diagram of a conventional rotary continuous-type device. DESCRIPTION OF SYMBOLS 1... Rotating body, 2... Fuel shearing piece, 3... Basket, 4... Rotating shaft, 5... Supply chute, 6...
・Discharge chute, 7...Fixed slab sub-agent Patent attorney Shige Okamoto 2 people Monju Figure 2 N～～ゞ! η(G) Figure 3 Figure 5 Figure 6 Figure 8 Figure 9 Figure 11 Procedural amendment January 21, 1986

Claims (1)

[Claims] a rotating body having a plurality of radial baskets, a supply chute for supplying fuel sheared pieces to the rotating body, a discharge chute for discharging processed sheared pieces from the rotating body, and a rotating body containing a fuel dissolving liquid; A nuclear fuel reprocessing melting tank characterized by comprising a fixed stub whose lower part is immersed.